The Preparation And Drug Controlled Release Of Octyl-dextran Porous Microspheres

In this paper, crosslinked microspheres were synthesized by reversed-phasesuspension polymerization using dextran as raw material, span-80as dispersing agentand epichlorohydrin (ECH) as crosslinker. Then octyl-dextran microspheres weresynthesized by coupling crosslinked dextran microspheres and ethylhexyl glycidylether (EHGE). Finally the octyl-dextran microspheres were added into the solution ofcyclohexane, and the porous structure was formed after drying the microspheres.The structure was determined by Fourier Transform Infrared (FTIR). The surfaceand inner morphology of microspheres was characterized by Scanning ElectronicMicroscope (SEM). The influences of preparation conditions on the octyl content ofoctyl-dextran porous microspheres were discussed. The dry densities, porosity, andequilibrium water content of the octyl-dextran microspheres were also measured.It was found that the octyl groups were grafted onto the surface of crosslinkeddextran microspheres successfully. These beads had spherical shape and porousstructure. The octyl content increased with the increasing of ethylhexyl glycidyl ether,temperature and time. The octyl content showed the tendency of increasing firstly andthen decreasing with the increasing of catalyzer content. The density decreased from1.61to1.21g/mL, porosity increased from80.68to95.05%and the equilibriumwater content presented an increasing (57.12to90.18%) firstly and then decreasingtrend (90.18to84.47%) with the increasing octyl content from0.49to2.28mmol/g.Octyl-dextran porous microspheres could effectively entrap water-soluble drugs.DOX-loaded octyl-dextran microspheres were prepared by absorbing the DOX withthe porous microspheres. The morphology of the drug-loaded microspheres wascharacterized by Optical Microscope (OM) and Scanning Electronic Microscope(SEM). The effects of microspheres/drug ratio, octyl content, catalyzer content on thedrug-loading capacity of octyl-dextran porous microspheres were discussed. Therepeating drug-loading ability of porous beads was also studied.The results showed that the drug loading efficiency increased with increasingmicrospheres/drug ratio, while the encapsulation efficiency decreased. Whenmicrospheres/drug ratio was4/1, the drug loading efficiency and the encapsulationefficiency reached10.20%and51.00%, respectively. The drug loading efficiencyshowed an increase first and then a decrease with increasing octyl content. The effectsof octyl-dexran/DOX (w/w) and catalyzer content on the release profiles were studied. The release rate of DOX increased as drug content increased but decreased withincreasing of catalyzer content. There were little differences in porosity and drugloading efficiency between recycling microspheres and the original microspheres.That was, the octyl-dextran porous microspheres had a good repeating drug-loadingability.